B+W makes three filters, 091, 092, and 093, all of which are useless on a D800.

091 is, as you pointed out, a Wratten 29 equivalent, and not much use in digital IR.

092 is a Wratten 70 equivalent, and it passes substantial deep red starting at 660nm. That's a real problem on a DSLR.

093 is a Wratten 87c equivalent, works very well on an IR modified camera, but the 800nm cutoff means a D800 is blind to that wavelength.

Some literature incorrectly identifies the B+W 092 and the Heliopan RG695 as Wratten 89b equivalent filters. This has caused any number of people considerable grief.

The B+W 091 filter is the same as a Wratten 29 dark red filter and not an IR filter. Heliopan also shows a red 29. The red 29 passes rays above 1 little over 600nm so this type of filter is very different then a 715nm IR or a 720nm IR.

True, but irrelevant, as B+W does not sell any filter that is useful on a D800.